The offshore Wheatstone project in Western Australia uses subsea big-bore gas wells as the preferred method of producing the field. Each of the highly productive wells represents a source of gas that, if accidently allowed to flow unhindered, could present an uncommonly difficult well‑control challenge. This paper details the engineering and operational planning performed to ensure that no uncontrolled hydrocarbon releases occur during the execution of the subsea big-bore gas wells and that, if a blowout were to occur, the response to such an event would be sufficient and robust.
The Wheatstone high-rate gas-well design, with its 9⅝-in. production conduit, represents the company’s initial attempt at implementing such a well. Because the design team’s combined engineering and execution experience included neither big-bore wells nor reservoirs of Wheatstone’s productive magnitude, well-control expectations were limited to anticipating needing only a single relief well in the event of a blowout. However, upon receipt of dynamic-kill simulations performed by consulting experts in that field, a new reality became obvious. That is, the combination of a large wellbore connected to the multidarcy Wheatstone gas reservoir has the potential to produce at more than 1 Bscf/D if flow is unconstrained; in some scenarios, this could require the use of up to four relief wells simultaneously injecting 15-lbm/gal drilling fluid to regain control....
Blowout Prevention and Relief-Well Planning for the Wheatstone Big-Bore Gas-Well Project
15 October 2016